1. Field of the Invention
This invention is directed to a novel class of compounds. More particularly, the invention relates to copolymers of certain cyclic nitrogenous and dibasic acid ester monomers.
2. Prior Art
Beale et al, U.S. Pat. No. 3,746,663, discloses a polymerization product of N-vinyl pyrrolidone and dibutyl maleate polymerized in the presence of a polyfunctional polyether polyol. The resulting materials contain a plurality of hydroxyl groups, e.g. the product of Example 1 of this product has a hydroxyl number of about 33. Such polyhydroxylic materials are excellent cellular foam stabilizers, but because the product contains free hydroxyl groups, they react with and destroy isocyanato groups, increase the viscosity of the isocyanate component and therefore, cause an undesirable modification of the activity of the finished stabilizer on storage in isocyanate-premix systems.